Breast cancer survivors who develop contralateral breast cancer have an increased risk of dying from breast cancer throughout a follow-up period of 10 or more years, according to a study of a cohort of 42,670 women diagnosed with breast cancer in Sweden. “The added risk is considerable if the [contralateral breast cancer] adds substantially to the total tumor burden and the interval time between the two tumors is short,” the investigators reported in the Journal of Clinical Oncology.
The risk of dying from breast cancer after contralateral breast cancer developed was also increased if the contralateral disease was advanced-stage, high-grade, and hormone-negative. Endocrine therapy not only reduced the risk of developing contralateral breast cancer, but also improved the prognosis if it did develop. The median survival time for women in the study was 6.7 years.
“The risk of developing [contralateral breast cancer] tended to be higher when women were young at diagnosis of the initial breast cancer, but the association was not statistically significant. The risk of [contralateral breast cancer] was almost twice as high for women with more than 10 metastatic lymph nodes vs women who were node negative. Large tumor size was associated with a modestly increased risk, but an extension of cancer to the chest wall and/or to the skin (T4) more than doubled the risk,” the authors noted.
“Our findings also indicate that some [contralateral breast cancers] may be metastases from the initial cancer and/or markers of active breast cancer disease and/or an undermined host defense. The findings suggest that the event of [contralateral breast cancer] marks a new clinical situation in terms of the investigation for metastases, treatment considerations, and follow-up strategy, and this situation needs to be covered in clinical guidelines,” the authors concluded.
Vichapat V, et al: J Clin Oncol 30:3478-3485, 2012.